/Engine/Source/Runtime/Engine/Classes/GameFramework/GameModeBase.h
Async version of PreLogin that MUST call OnComplete when done, otherwise incoming client connections will hang or timeout. This allows servers to make requests to other services for verification of login credentials without blocking the game thread.Bydefault, this callsPreLogin()and OnComplete immediately to not break backwards compatibility. When overriding this, be sure checks in PreLogin are also run, and that the GameModePreLoginEvent is broadcast.
virtual void PreLoginAsync ( const [FString](API\Runtime\Core\Containers\FString) & Options, const [FString](API\Runtime\Core\Containers\FString) & Address, const [FUniqueNetIdRepl](API\Runtime\Engine\GameFramework\FUniqueNetIdRepl) & UniqueId, const [FOnPreLoginCompleteDelegate](API\Runtime\Engine\GameFramework\AGameModeBase\FOnPreLoginCompleteDelegate) & OnComplete )